JPH0337096B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a combustion safety device that changes the position of a flame rod to enable variable combustion amount and stable flame detection during oxygen-deficient combustion.

Conventional technology Conventional flame detectors are set with the flame rod fixed in relation to the flame hole, and when switching the combustion amount, the flame detection current of the flame rod changes greatly, and as shown in Figure 2, the flame detection current of the flame rod changes greatly. The detection level increases during low combustion, and depending on flame fluctuations, it may reach the abnormal detection level, and the characteristics during oxygen deficiency also cause differences in flame current as shown in Figure 3, resulting in changes in combustion amount. The detected oxygen concentration changed depending on the temperature.

Problems to be Solved by the Invention As described above, in the conventional technology, varying the combustion amount causes a difference in flame current, which changes the detected oxygen concentration, making safe flame detection difficult.

Means for Solving the Problems The present invention has been made in view of the above problems.
The flame rod, which faces the vicinity of the combustion flame, is moved using a shape memory alloy that is activated by changes in combustion temperature caused by switching the combustion amount, so that the flame rod is always located within the combustion flame.

Operation As shown in Figure 4, flame rod 1 is placed in a combustion flame, and alternating current AC voltage 3 is applied between it and ground electrode 2. It is ionized and an electromotive force is generated. The ion current or flame current of this is used, and when the flame rod is in contact with the flame, the flame current changes greatly, and at the detection level shown in Figure 2, for example, the air-fuel ratio input
With a burner set at 0.8, high combustion amounts are well above the detection level and there is no problem, but low combustion amounts are near the detection level, which is an area where fluctuations in combustion amount and air amount can reach the detection level and cause abnormality detection. It is in. In response to the above-mentioned changes in combustion rate, the position of the flame rod is moved so that it is always within the flame by using a shape memory alloy and taking advantage of the temperature difference due to the change in combustion rate. Try to get the following. This makes it possible to detect changes in combustion amount, air-fuel ratio, and oxygen concentration during oxygen deficiency at the same level.

Embodiment FIG. 1 shows a schematic diagram of a combustion device, in which a carburetor cylinder 10
A heater 11 is buried inside the tip of the vaporizer cylinder 1.
A lower plate 12 whose central part is open from the upper end of the cylinder 0 and whose end face is bent, a combustion tube 13 made of wire mesh in contact with the bent surface, and an upper plate 14 bent downwards are provided on top of the combustion cylinder 13. The blower tube 15 passes through the side wall of the vaporizing tube 10.
are connected to the blower fan 16. A thin fuel tube 17 faces into the vaporizing tube 10 from the middle of the blast tube 15, and the other end is connected to a fuel tank 19 via a fuel pump 18. Reference numeral 20 denotes a dish-shaped base for holding the carburetor cylinder 10. A support plate 21 is attached to a part of the base, one end is provided near the combustion cylinder 13, and a spring material 22 made of a shape memory alloy is fixed thereto, and the other end is attached to a frame rod 23. The support plate 21 and the base 20 are fixed to a fixed band 25 wrapped around the frame rod insulator 24 of
In between, a stroke guide 26 is formed along which the frame rod 23 can move. The controller 2 is connected to the frame rod 23 and the base 20 via lead wires.
7 is connected. 28 is an exhaust pipe arranged above the base.

Next, to explain the operation, the heater 11 embedded in the vaporization tube 10 is energized to heat the inside of the vaporization tube 10 to a high temperature range, and then the blower fan 16 arranged at the rear of the ventilation passage 15 is driven to blow combustion air into the vaporization tube. After the fuel is introduced into the fuel tube 10, a fuel pump 18 disposed in the middle of the fuel tube 17 is driven to draw fuel from the fuel tank 19, and the fuel is scattered from the tip of the fuel tube 17 into the vaporizer tube 10. Here, since the inside of the carburetor cylinder 10 is maintained at a high temperature, the scattered fuel instantaneously evaporates, becomes vaporized gas, is mixed with fuel air, and exits from the opening of the lower plate 12 as a premixture to the upper plate. The combustion tube 13, which is made of a cylindrical wire mesh formed between the combustion chamber 14 and the combustion tube 14, is emitted to the surroundings, and is ignited by an igniter (not shown) to form a combustion flame on the surface of the wire mesh. Exhaust gas is discharged upward from the exhaust pipe 28. Next, the tip of the flame rod 23 is positioned near the wire mesh surface of the combustion tube 13, and the fixing band 2 is attached to the flame rod insulator 24.
5 is attached, and a spring material made of shape memory alloy is attached to it.
22 is attached to the support plate 21, and the heat conduction from the support plate 21 and the stroke guide 26 are placed close to the combustion cylinder.
Spring material 22 made of a shape memory alloy is located at position _L1 in the figure during the initial state and low combustion rate, and at position _L2 in the figure when the combustion rate is high. It is something that rises and moves. L ₁ and L ₂ at this low and high combustion
The position is the range where it can come into contact with the flame formed on the surface of the wire mesh of the combustion tube 13, and the combustion amount changes and the flame rod 23 can come into contact with the flame depending on the size of the flame. Since the characteristics are maintained even when the combustion amount is low, there is a margin for the detection level, and a stable state can be maintained even if the combustion amount and air amount fluctuate and the air-fuel ratio changes slightly. In addition, when there is a lack of oxygen in the room, in order to maintain the same characteristics when the combustion amount is high as shown in Figure 3 and when the combustion amount is low, the oxygen concentration that indicates the detection level indicating an abnormality in the case of oxygen deficiency is the same at 18%.
You can cut it with . The spring material 22 made of a shape memory alloy maintains the temperature at the _L1 position from low combustion to non-combustion, and moves along the stroke guide 26 to the _L2 position as the temperature rises at high combustion. The flame rod is always kept in contact with the flame to give a stable flame current to the controller 27 as explained in Fig. 4, and the fuel pump 18 is stopped when the abnormality detection level is reached. It is.

Effects of the Invention The present invention connects a spring material made of a shape memory alloy to the fixing band of the frame rod, and makes use of the temperature change caused by the variable combustion amount to move the flame rod by thermal conduction and radiant heat, thereby achieving the following effects. .

(1) By detecting the temperature when the combustion amount changes and moving a spring material made of a shape memory alloy and bringing it into contact with the flame at a position corresponding to the size of the combustion flame, the flame current can be changed, for example, when the combustion amount is high. Since the flame current can be maintained at the same level as the flame current, it is possible to detect changes in the air/heat ratio input using a stable flame current.

(2) Since the same level of flame current can always be obtained regardless of changes in combustion amount even during oxygen deficiency, it is possible to limit the oxygen concentration that is the abnormality detection level (for example, O ₂ 18
%), it is possible to detect a safe oxygen concentration by preventing early or late termination of the oxygen concentration.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of a combustion device according to an embodiment of the present invention, FIG. 2 is a characteristic diagram of air-fuel ratio input and flame current, and FIG. 3 is a characteristic diagram of oxygen concentration and flame current.
FIG. 4 shows a diagram of the principle of the frame rod. 13... Combustion tube, 21... Support plate, 22... Spring material, 23... Frame rod, 24... Frame rod insulator, 25... Fixing band.

Claims (1)

[Claims] 1. Arranging a flame rod near the combustion tube, attaching a fixing band to the insulator of the flame rod, attaching the other end of a spring material made of a shape memory alloy with one end connected to the fixing band to the support plate, and One end of the support plate faces the vicinity of the combustion tube, and the flame rod is configured so that it is always in contact with the combustion flame by moving the spring material due to changes in heat conduction and radiant heat of the support plate in response to changes in the amount of combustion. A combustion safety device configured to move.